5-Phenoxy-1(3H)-isobenzofuranone is a useful intermediate in the preparation of the derivatives of isoquinoline. Example 3 of WO 2014014834 A1 discloses a method for its preparation:

The reaction follows Ullmann diaryl ether synthesis conditions and gives a fair yield of 72%. This method uses a large amount of copper bromide, which is carried as heavy metal waste into the waste system.
Example 1 of WO 2013134660 A1 provides a method of preparing a compound of Formula I from a compound of Formula II, in which CuCl, 2,2,6,6-tetramethyl-heptane-3,5-dione (TMHD), and expensive cesium carbonate are used as reactants and reagents. Furthermore, the industrial process required to produce 5-bromo-1(3H)isobenzofuranone (Formula II) is a long and complicated process.

The process for preparing the intermediate of Formula II has several obvious disadvantages, including (1) the requirement for four reaction steps, (2) generation of a large amount of heavy metal waste, (3) performing a diazotatization reaction that generates a potentially unstable diazonium salt, and (4) the difficulty of separating the desired 5-amino-1 (3H)isobenzofuranone of Formula Va from its 6-isomer of Formula Vb. This process is widely discussed in the scientific literature and published patents, see for Example WO 2006/103550 A1.
Chem. Pharm. Bull. (1978) 26(2): 530-538 describes a method for preparing 5-nitro-1(3H)isobenzofuranone of Formula XIII from which 5-bromo-1(3H)isobenzofuranone of Formula II can be prepared following the same sequence of reduction, diazotation and bromo-replacement set forth in Scheme II. But, the NaBH4-reduction only gives 21% of the desired product of Formula XIII.

Therefore, there is a need for a green and economically favorable process for producing 5-phenoxy-1(3H)-isobenzofuranone. The desired process has fewer steps, produces less waste, recycles chemical reactants, and provides high regioselectivity during the reduction to form the lactone.